In gene therapy, patients carrying identified defective genes are supplemented with the copies of the corresponding normal genes. However, genes (DNA), the polyanionic macromolecules and the cell surfaces of the biological membranes both being negatively charged, spontaneous entry of normal copies of genes into the target cells of patients is an inefficient process (because of electrostatic repulsion). This is why the past decade has witnessed an unprecedented upsurge of global interest in developing efficient gene delivery reagents for introducing normal genes into the target cells of patients suffering from various genetic (inherited) diseases such as cystic fibrosis, Gaucher's illness, Fabry's disease etc. Many gene delivery reagents (also known as transfection vectors) including retrovirus, adenovirus, and cationic amphiphilic compounds (i.e. compounds containing both polar and non-polar functionalities) are being used as the carriers of polyanionic genes in combating hereditary diseases in gene therapy. The amphiphilic nature (presence of both polar and non-polar regions in the molecular structures) of the compounds designed to deliver therapeutically actives molecules, ensures smooth interaction of these carrier molecules with the polar and non-polar regions of plasma membranes, compartments within the cells and the biologically active molecules itself. At physiological pH, the cationic amphiphiles in the form of liposomes or micelles associate favorably with the negatively charged regions of the macromolecular polyanionic DNA enhancing the intracelluar uptake of the resulting complex between the cationic lipids and the negatively charged DNA. Reproducibility, high degree of targetability and low cellular toxicity are increasingly making the cationic amphiphiles the transfection vectors of choice in gene therapy.